1. Field of the Invention
The present invention relates to a method and device for assembling and adjusting the adjustable nozzle mechanism of a radial flow turbine used as the supercharger of an internal combustion engine (exhaust turbocharger) and so forth, the turbine being configured so that the actuating gas flows from the spiral scroll formed in the turbine casing to the turbine rotor in the radial direction via a plurality of nozzle vanes of variable wing angle to rotate the turbine rotor.
2. Description of the Related Art
In order to make a good match of the exhaust gas flow rate of the engine with that with which the supercharger operates in the optimum operation condition, superchargers equipped with variable capacity turbines capable of changing the exhaust gas flow rate in accordance with the operating condition of the engines, have been in wide spread use in recent years in internal combustion engines with superchargers.
A supercharger with such a variable capacity turbine is equipped with an adjustable nozzle mechanism in order to change the turbine capacity. The adjustable nozzle mechanism can change the wing angle of the nozzle vanes through rotating the nozzle vanes by means of an annular link mechanism (ring assembly) which is driven to rotate around the rotation center of the turbine rotor by an actuator by way of an actuator rod.
For a method to achieve assembling and adjustment of such an adjustable nozzle mechanism, an invention of Japanese Patent No. 3,085,210 has been proposed.
In the concerned invention, a jig should be placed in the inner radius of the nozzle vane to perform the setup for perfect closing of the nozzle vane and the ring assembly to be driven for rotations around the turbine rotor shaft. The jig therein can be put in contact with the rear edge of the nozzle vane, wherein the stopper pin is mounted after the nozzle vane and the lever plates are welded together upon putting the nozzle vane in contact with the jig in the state that the stopper pin, that is to be fitted into the long slots located at multiple positions along the circumferential direction of the link plate, is made non-functional or non-existing, and upon fitting the matching pin into the phase matching hole to finalize the entire ring assembly in the perfect closing phase.
However, according to the invention of Japanese Patent No. 3,085,210, the two different processes are required, one of which is to put the jig in contact with the nozzle vane in the nozzle vane-free state wherein the stopper pin to be fitted into the long slots of the link plate is non-functional, and the other process is, keeping the above state, to engage the phase matching hole and the phase matching pin, and set the entire ring assembly in the perfect closing phase, then weld the nozzle vane and the lever plate, and fix the stopper pin. This makes assembly and adjustment work of the adjustable nozzle mechanism troublesome, requiring a lot of man-hours resulting in increased costs.
According to the conventional art, the setup for perfect closing of the adjustable nozzle mechanism is done by fitting each stopper pin into each long slot provided on the link plate along the circumferential direction and matching the contact angle with the lever plate by contacting the tail end of the nozzle bane with the jig, so variations in setup for perfect closing tend to occur resulting in setup error. Moreover, as the perfect closing position of the adjustable nozzle mechanism is influenced by the accuracy of such constituent parts as described above, the adjustment is difficult after assembling turbine.
In consideration of the problems with the conventional art mentioned above, the object of this invention is to provide a method and device for assembling and adjusting a variable capacity turbine, which simplifies the assembling and adjustment process of an adjustable nozzle mechanism to reduce man-hours and costs for assembling and adjustment, is capable of setting up the positions of the nozzle vanes of an adjustable nozzle mechanism with good accuracy without influenced by the accuracy in dimension of the constituent parts such as nozzle vanes, annular link assemblies (ring assembly), etc., and is capable of adjusting the adjustable nozzle mechanism whenever necessary even after they are assembled.
In order to solve the concerned problems, the invention proposes a method of assembling and adjusting a variable capacity turbine having a plurality of nozzle vanes disposed along the circumferential direction of a turbine rotor in the inner radius side of the spiral scroll formed in the turbine casing and supported free of rotation on the supporting part of the nozzle mount, the turbine rotor being supported in the turbine casing for rotation around the rotation axis; and an annular link mechanism mounted free of rotation with respect to the rotation axis, provided with connection parts each of which is connected with the driving part of each of said nozzle vanes, and connected with the output end of an actuator; characterized in that said plurality of the nozzle vanes are temporarily encircled and bound with a binding member capable of binding/releasing such as belt, etc. in a state the vanes are perfectly closed with the vanes contacting to each other, then the driving part of each nozzle vane is fixed to the connection parts of the annular link mechanism with the vanes in the temporarily bound state.
It is preferable that the nozzle pins each of which is fixed to each of the nozzle vanes and supported in said nozzle mount free of rotation are fixed to lever plates constituting the connection parts of the annular link mechanism by means of staking or the like in the temporarily bound state with the vanes perfectly closed.
It is also preferable that the constituent parts can be transferred or installed into the turbine in the state of a nozzle assembly temporarily fixed to the supporting part of said nozzle mount by encircling and binding with a binding member capable of binding/releasing such as belt, etc. in a state the vanes are perfectly closed with the vanes contacting to each other.
The invention is also characterized in that a nozzle vane side mating part is provided in the nozzle mount, a link side mating part is provided in the annular link mechanism, a jig is prepared of which at an end side is formed a portion for determining the nozzle vane side position and at the other end side is formed a portion for determining the annular link mechanism side position, said portion for determining the nozzle vane side position of said jig is mated with said nozzle vane side mating part of said nozzle mount and said link side mating part is mated with said portion for determining the annular link mechanism side position with each nozzle vane temporarily fixed in perfect closing position, and the perfect closing position of the nozzle vane side and the annular link mechanism side is set up by way of the nozzle vane combining part of said nozzle mount by fixing said nozzle pins to said lever plate by staking or the like.
It is preferable that said nozzle mount is provided with a mating hole as said nozzle vane side mating part, said jig is provided with a pin-like protrusion as said portion for determining the nozzle vane side position and a contact face capable of contacting with a face of the link plate constituting said annular link mechanism as said portion for determining the annular link mechanism side position, and positioning is done by allowing said face of the link plate to contact with said contact face of said jig in the state said protrusion of said jig is inserted in said mating hole of said nozzle mount.
It is also preferable that said nozzle mount is provided with a mating hole as said nozzle vane side mating part, said jig is provided with a pin-like protrusion as said portion for determining the nozzle vane side position and a groove capable of meshing with the connection pin of the link plate constituting said annular link mechanism as said portion for determining the annular link mechanism side position, and positioning is done by allowing said connection pin of the link plate to mesh with said groove of said jig in the state said protrusion of said jig is inserted in said mating hole of said nozzle mount.
The invention proposes a device for assembling and adjusting a variable capacity turbine having a plurality of nozzle vanes disposed along the circumferential direction of a turbine rotor in the inner radius side of the spiral scroll formed in the turbine casing and supported free of rotation on the supporting part of the nozzle mount, the turbine rotor being supported in the turbine casing for rotation around the rotation axis; and an annular link mechanism mounted free of rotation with respect to the rotation axis, provided with connection parts each of which is connected with the driving part of each of said nozzle vanes, and connected with the output end of an actuator; characterized in that a binding member is provided which encircles and binds said plurality of the nozzle vanes to fix them in perfect closing position with the vanes contacting to each other, said binding member being capable of binding/releasing, and a minimum stopper is provided for limiting the shift of the linkage connecting said actuator and annular link mechanism toward perfect closing side.
It is preferable that a maximum stopper is provided for limiting the shift of the linkage toward full open side.
According to the present invention, a plurality of nozzle vanes are encircled with a binding member capable of binding/releasing to temporarily fix the vanes in a state the vanes are perfectly closed with the vanes contacting to each other; then the positioning of the nozzle vane side, i.e. the nozzle assembly side relative to the annular link mechanism side, is performed by use of jigs in the temporally fixed state; and the driving part of each nozzle vane is fixed to each connection part of the annular link mechanism; so adjustment of the perfect closing position is unnecessary in nozzle assembling process, and the adjustment of perfect closing position is possible by means of a minimum stopper in the assembled state of the variable capacity turbine.
The adjustable nozzle mechanism is set by this simple method, in which a plurality of the nozzle vanes are bound by an encircling binding member, the relative position of the nozzle vane side to the annular link mechanism side is determined by use of jigs, and each nozzle vane is fixed to each lever plate, which eliminates the necessity of adjustment of perfect closing position in the assembling of the nozzle vanes, the assembling and adjustment procedure is extremely simplified compared with the prior art disclosed on Japanese Patent No. 3085210 in which the adjustment of perfect closing position is done in the assembling process of nozzle vanes by use of a plurality of long slots in the link plate, stopper pins, and a jig. Therefore, man-hours for assembling and adjustment decreases and accordingly manufacturing costs is reduced.
According to the present invention, a plurality of nozzle vanes are bound by encircling them with a binding member to determine perfect closing position, each nozzle vane is fixed to the lever plate 2, and the adjustment of perfect closing position is done as a whole by a minimum stopper in the assembled state of the variable capacity turbine, so errors in dimensions of the nozzle side assembly including nozzle vanes and annular link mechanism side assembly including link plate and linking parts in assembled state can be absorbed. Therefore, the setting of the adjustable nozzle mechanism is possible with good accuracy without influenced by the accuracy in dimensions of the constituent parts and without influenced by the accuracy in dimensions of the nozzle side assembly and annular link mechanism side assembly, contrary to the case of the prior art disclosed on Japanese Patent No. 3085210 whereby variation in the setting of perfect closing position of each nozzle vane occurs because the adjustment of perfect closing position is done in nozzle vane assembling process by use of a plurality of long slots in the link plate, stopper pins, and a jig, which results in a setting error. The adjustable nozzle mechanism with high accuracy of setting according to the invention is adaptable to various specifications.
It is also possible that the variable capacity turbine according to the invention has the same function as the exhaust brake of truck and so forth by adjusting the perfect closing position by the minimum stopper as desired. The adjustment of the full open position of the nozzle vanes is possible by the maximum stopper in the assembled state of the variable capacity turbine.
Further, according to the invention, the adjustable nozzle mechanism assembly can be transferred and installed into the turbine in the state in which a plurality of the nozzle vanes are temporarily encircled and bound with the binding member and fixed to the supporting parts of the nozzle mount 4, damage to the constituent parts of the nozzle assembly due to vibration or impact is prevented.